Small unmanned aerial vehicle (SUAV) shipboard recovery system

ABSTRACT

Systems, devices, and methods for impacting, by a small unmanned aerial vehicle (SUAV), a net having at least three sides; and converting the kinetic energy of the SUAV into at least one of: elastic potential energy of one or more tensioned elastic cords connected to at least one corner of the net, gravitational potential energy of a frame member connected to at least one corner of the net, rotational kinetic energy of the frame member connected to at least one corner of the net, and elastic potential energy of the frame member connected to at least one corner of the net.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/698,770, filed Apr. 28, 2015, which claims priority to and thebenefit of U.S. Provisional Patent Application No. 61/986,041, filedApr. 29, 2014, the contents of both of which are hereby incorporated byreference herein for all purposes.

TECHNICAL FIELD

Embodiments relate generally to systems, methods, and devices for smallunmanned aerial vehicles (SUAV), and more particularly to recovery ofSUAV.

BACKGROUND

Existing SUAV recovery methods include launching a smaller recoveryvessel or boat from a ship to retrieve an SUAV by hand from the water,which may endanger crew aboard the vessel. Existing net-based recoverysystems are overly complex. Many of these systems require substantialcomponents. Additionally, many of these systems require specialequipment, such as cranes, to set-up on ships; require substantialavailable ship deck space to set-up and/or operate; have to be locatedin areas of air turbulence generated by the ship's structure; and/orplace the landing target in the vicinity of ship crew members and/orequipment, which could lead to disastrous effects in the case of asystem failure.

SUMMARY

Exemplary method embodiments may include: impacting, by a small unmannedaerial vehicle (SUAV), a net having at least three sides; and convertingthe kinetic energy of the SUAV into at least one of: elastic potentialenergy of one or more tensioned elastic cords connected to at least onecorner of the net, gravitational potential energy of a frame memberconnected to at least one corner of the net, rotational kinetic energyof the frame member connected to at least one corner of the net, andelastic potential energy of the frame member connected to at least onecorner of the net. Additional method embodiments may include securingthe SUAV in the net after converting the kinetic energy of the SUAV bydetachable entanglement of the SUAV in the net. In additional methodembodiments, securing the SUAV in the net may further include detachablyentangling at least one barb in the net, wherein the at least one barbis disposed on a fuselage of the SUAV. In additional method embodiments,the frame member may be a boom. In additional method embodiments, theboom may connected to a gooseneck connector having a vertical hinge anda horizontal hinge. In additional method embodiments, at least onecorner of the net may be connected to a mast at a position distal from aportion of the mast connected to the gooseneck connector. In additionalmethod embodiments, at least one corner of the net is connected to aportion of a ship. Additional method embodiments may include removing,by a deck handler on the ship, the SUAV from the net. In additionalmethod embodiments, retrieving the SUAV from the net may further includerotating the boom to a location proximate to an edge of a ship. Inadditional method embodiments, retrieving the SUAV from the net mayfurther include lowering the mast telescopically. Additional methodembodiments may include reducing, prior to impact, a closing speed ofthe SUAV. In additional method embodiments, reducing the speed of theSUAV further comprises cutting power to a propeller of the SUAV.

Exemplary system embodiments may include a small unmanned aerial vehicle(SUAV) recovery system including: a net having at least three corners;and a boom connected to at least one corner of the net; where energy ofan impact of the SUAV into the net is progressively transferred by atleast one of: a vertical rotation of the boom in a direction towards theimpact of the SUAV, and a horizontal rotation of the boom in a directionaway from the impact of the SUAV. In additional system embodiments,energy of the impact of the SUAV may also be transferred by deformationof the net. In additional system embodiments, energy of the impact ofthe SUAV may also be transferred by a progressive bending of the boom.Additional system embodiments may include: one or more tensioned elasticcords attached to at least one corner of the net; where energy of theimpact of the SUAV may also be transferred by deformation of the one ormore tensioned elastic cords. Additional system embodiments may include:three or more rings attached to the perimeter of the net; and three ormore lines, where each side of the net may be slidably connected to oneof the three or more lines by one or more of the three or more rings.Additional system embodiments may include: a mast, where the mast may beoriented perpendicular to the boom; a gooseneck connector, where themast may be connected to the gooseneck connector by a mast connector,and where the boom may be connected to the gooseneck connector by a boomconnector; a lower clamp, where the lower clamp may be connected to thegooseneck connector; and a stanchion, where the lower clamp may beattached to a stanchion. Additional system embodiments may include: anupper clamp, where the upper clamp may be disposed about an upperportion of the stanchion and a portion of the mast. In additional systemembodiments, the stanchion may be on a ship, and the mast, gooseneckconnector, boom, and triangular net may be disposed over an edge of theship. In additional system embodiments, the mast and the boom may betelescopically adjustable in length. In additional system embodiments, asquare mesh size of the net may be smaller than a cross-sectional sizeof a fuselage of the SUAV. Additional system embodiments may include:one or more barbs disposed on a fuselage of the SUAV, where the one ormore barbs may be sized to detachably entangle in the net after impact.

BRIEF DESCRIPTION OF THE DRAWINGS

The components in the figures are not necessarily to scale, emphasisinstead being placed upon illustrating the principals of the invention.Like reference numerals designate corresponding parts throughout thedifferent views. Embodiments are illustrated by way of example and notlimitation in the figures of the accompanying drawings, in which:

FIG. 1A depicts an exemplary embodiment of a small unmanned aerialvehicle (SUAV) shipboard recovery system;

FIG. 1B depicts the exemplary SUAV shipboard recovery system of FIG. 1Awhere a SUAV impacts a recovery net causing the boom to swing up toabsorb the energy from the impact of the SUAV;

FIG. 1C depicts the exemplary shipboard recovery system of FIGS. 1A-1Bwhere the boom drag line is eased and the mast is lowered to allowremoval of the SUAV by a person on the ship;

FIG. 1D depicts a top view of the exemplary shipboard recovery system asthe net billows outwards due to wind and the closing speed of the SUAVis reduced;

FIG. 1E depicts a top view of the exemplary shipboard recovery system ofFIG. 1D as the net is deformed due to SUAV impact;

FIG. 1F depicts a top view of the exemplary shipboard recovery system ofFIGS. 1D-1E as the impact of the SUAV causes deformation of the elasticcords and lines connected to the net;

FIG. 1G depicts a top view of the exemplary shipboard recovery system ofFIGS. 1D-1F as the impact of the SUAV causes the boom to lift verticallyand progressively bend;

FIG. 1H depicts a top view of the exemplary shipboard recovery system ofFIGS. 1D-1G as the impact of the SUAV causes the boom to rotatehorizontally towards the bow of the ship;

FIG. 2A depicts an exemplary net having lines secured to each side ofthe net and elastic cords secured to one or more corners of the net;

FIG. 2B depicts an exemplary ring secured to a side of the net forattachment to a line along the side of the net;

FIG. 3A depicts a side view of an exemplary barb secured to a fuselageof the SUAV;

FIG. 3B depicts a top view of four exemplary barbs secured to thefuselage of the SUAV near and about the center of mass of the SUAV;

FIG. 4A depicts an exemplary gooseneck connector attached to a shipstanchion by a lower clamp and an upper clamp with the boom extendedaway from the ship;

FIG. 4B depicts the exemplary gooseneck connector of FIG. 4A showingvertical and horizontal rotation of the boom;

FIG. 5A depicts a quick release system between the exemplary lower clampand the gooseneck connector quick release block with an indentation inthe clamp quick release block shown with dashed lines;

FIG. 5B depicts a quick release system between a second lower clampsized for a different stanchion and the gooseneck connector quickrelease block shown in FIG. 5A with a second indentation in the secondclamp quick release block shown with dashed lines;

FIG. 6 depicts the system in a stored state with the mast and boomextending vertically and a tether attached from the gooseneck connectorto another portion of the ship;

FIG. 7 is a flowchart of a setup of an exemplary embodiment of the SUAVshipboard recovery system; and

FIG. 8 is a flowchart of an exemplary embodiment of the SUAV shipboardrecovery system.

DETAILED DESCRIPTION

The present invention allows for recovery of small unmanned aerialvehicles (SUAV) aboard a ship, where kinetic energy from the SUAV isprogressively transferred to a recovery system. This kinetic energytransfer may be done in a manner to reduce or minimize the decelerationthat the SUAV experiences, given the size parameters of the recoverysystem, and thus reduce the potential for damage to the SUAV. Therecovery system may be connected to a stanchion on a ship by a lowerclamp connected to a gooseneck connector by a quick release system. Thegooseneck connector may include a horizontal hinge, a vertical hinge, aboom connector, and a mast connector. During operation, the framemembers, i.e., the mast and/or boom, may be oriented perpendicular toone another, and the boom may be perpendicular to the ship's side. Atriangular net may be suspended from a tip of the boom, a tip of themast, and a point on the ship's deck's edge. The boom, mast, and/or netmay be supported by one or more stays and/or tensioned elastic cords.When an SUAV flies into the triangular net, the energy of the SUAV maybe absorbed by lifting the weight of the boom vertically, via thehorizontal hinge; rotating the boom horizontally towards the bow of theship, via the vertical hinge; progressively bending the boom; deformingthe elastic cords attached to the net; impacting and moving the netand/or lines attached to the net; via the air resistance of the netbeing moved through the air; impacting the net at an angle; the forwardmovement of the ship reducing the closing speed of the SUAV with thesystem; and/or deforming the net. The SUAV may be trapped in thetriangular net by entanglement of its propeller, wingtips, one or morebarbs attached to the fuselage of the SUAV, and/or any other componentof the SUAV, as well as the part or whole of the SUAV, or componentsthereof, being enveloped by the net. The SUAV may be quickly retrievedfrom the net by a deck handler on the ship, without the need to deploy asmall vessel or boat from the ship to retrieve the SUAV in the water.

FIG. 1A depicts an exemplary embodiment of a small unmanned aerialvehicle (SUAV) shipboard recovery system 100. The system 100 may includea mast 102 and a boom 104, which may be connected to a ship 106 by agooseneck connector 108. The gooseneck connector 108 may be attached toa stanchion 110, e.g., a vertical railing support, on the ship 106 by alower clamp 112. The mast 102 and/or boom 104 may be telescopicallyadjusted to expand and/or contract in length. In some embodiments, themast 102 and/or boom 104 may be fixed in length. The mast 102 and/orboom 104 may be made from a flexible, non-conductive, and waterresistant material, e.g., fiberglass. Any ends of the mast 102 and/orboom 104, including each telescoping end, may be reinforced, e.g., withKevlar® by DuPont™ of Goleta, Calif., to prevent splitting from energyabsorbed by the SUAV 109 impact. The SUAV 109 may be a high wing aerialvehicle, e.g., a Puma™ AE by AeroVironment, Inc. of Monrovia, Calif. Thesystem dimensions may be modified to accommodate other SUAV types. Themast 102 may be oriented perpendicular to the ship's deck. The boom 104may be oriented perpendicular to the ship's side. The boom 104 may berotated to be oriented perpendicular to the mast 102 in a firstposition, when the system 100 is not receiving an SUAV 109. The boom 104may also be rotated to be oriented parallel to the mast 102 (See FIG. 6)in a storage position. The mast 102 may be supported by tensionedrigging, e.g., a beam stay 114, a forestay 116, and an aft stay 118. Thetensioned rigging (114, 116, 118) may be attached from a portion of themast 102 distal from the gooseneck connector 108 to a respectivelocation (123, 125, 126) on the deck of the ship 106. The boom 104 mayheld in the first position by running rigging, e.g., a drag line 120 anda lower net line 122. The running rigging (120, 122) may be connectedfrom a portion of the boom 104 distal from the gooseneck connector 108to a respective location (125, 126) on the deck of the ship 106. Thedrag line 120 and lower net line 122 may be a single continuous line,which may be threaded through an eyelet 127 disposed on the portion ofthe boom 104 distal from the gooseneck connector 108. In someembodiments, a trim weight (not shown) may be attached proximate to theeyelet 127. The trim weight may be used to keep the boom 104 fromraising up during heavy winds. The trim weight may be increased ordecreased based on the wind and/or weather conditions as needed. Therunning rigging (120, 122) may allow the boom 104 to swing, e.g.,towards the bow relative to the ship 106, in response to impact by anSUAV 109 in a second position.

The system 100 may also include a net, such as a triangular net 124. Inother embodiments, the net may have more than three sides and varyingshapes. The triangular net 124 may be suspended between the portion ofthe mast 102 distal from the gooseneck connector 108, the portion of theboom 104 distal from the gooseneck connector 108, and a portion of theship 106 via a ship net connector 126. One or more corners of thetriangular net 124 may be attached by one or more elastic cords (128,130), e.g., bungee cords. In some embodiments, all corners of the netmay be attached by one or more elastic cords. The elastic cords (128,130) may be tensioned by pulling in the drag line 120. A net line 132may be integrated into the triangular net 124 between the mast 102 andthe boom 104. The lower net line 122 may be integrated into thetriangular net 124 between the boom 104 and the ship net connector 126.The aft stay 118 may be integrated into the triangular net 124 betweenthe mast 102 and the ship net connector 126. The triangular net 124 maybe inclined such that the portion of the triangular net 124 proximate tothe mast 102 slopes away from the portion of the triangular net 124proximate to the lower net line 122. The slope of the triangular net 124may prevent the SUAV 109 from falling out of the triangular net 124after impact, and may act to reduce loads on the SUAV by impacting thenet at an angle. In some embodiments with barbs attached to the fuselageof the SUAV (See FIGS. 3A-3B), the net may be aligned at, or near, avertical orientation relative to the ship's deck. The portion of themast 102 distal from the gooseneck connector 108 may include one or moresensors and/or indicators, e.g., a wind indicator 134, which may be usedby an operator of the SUAV 109 for reference in accurately guiding theSUAV 109 into the triangular net 124.

The system 100 may be disposed over the side of the ship 106 and abovethe water. The positioning of the system 100 takes up no, or minimal,deck space on the ship 106. The location of the system 100 also reducesthe effects of turbulence, which may be caused by air moving over one ormore ship structures while the ship is in motion. The reduced turbulencemay result in the triangular net 124 holding its shape and increasedmaneuverability of the SUAV 109 as it approaches the system 100 forlanding.

FIG. 1B depicts the exemplary SUAV shipboard recovery system of FIG. 1Awhere the SUAV 109 impacts the triangular net 124 causing the boom 104to swing up to absorb the energy from the impact of the SUAV 109. As theSUAV 109 impacts the triangular net 124, the energy from the SUAV 109 isabsorbed by moving and/or deforming the triangular net 124; deformingthe one or more tensioned elastic cords (128, 130) connected to at leastone corner of the triangular net 124; lifting the weight of the boom104; rotating the weight of the boom 104 towards the bow of the ship;bending the boom 104; deforming the aft stay 118, lower net line 122,and/or net line 132; and/or deforming the drag line 120. The SUAV 109impact may convert the kinetic energy of the SUAV 109 into at least oneof: increased momentum of the net; air drag of the net; elasticpotential energy of the one or more tensioned elastic cords (128, 130),gravitational potential energy of the boom 104, rotational kineticenergy of the boom 104, and elastic potential energy of the boom 104.The SUAV 109 velocity is self-modulated by the height to which the boom104 is lifted, rotated, and/or bent. The boom 104 may swing and/or bendtowards the bow relative to the ship 106 to absorb additional energy,e.g., during impact of the SUAV 109 in the second position. The boom 104may be self-centered to the first position, perpendicular to the ship'sside, by action of the gooseneck connector 108, drag line 120, and/orlower net line 122.

FIG. 1C depicts the exemplary shipboard recovery system of FIGS. 1A-1Bwhere, after the SUAV 109 has substantially come to rest in the net 124,the boom drag line 120 is eased and the mast 102 is lowered to allowremoval of the SUAV 109 by a person, e.g., deck handler, on the ship106. Once the SUAV 109 is secured in the triangular net 124, e.g., byentanglement and/or envelopment of the SUAV 109 and/or one or more ofits components and/or barbs, the drag line 120 may be let out to allowthe boom 104 to rotate aftward relative to the ship 106, until the boom104 is proximate to the ship's deck's edge. The mast 102 may be loweredtelescopically and/or the boom 104 may be shortened telescopically, asneeded, to assist in safe removal of the SUAV 109 from the triangularnet 124. Once the SUAV 109 is removed, the system may return to itsfirst position by pulling in the drag line 120, extending thetelescoping mast 102, and/or extending the telescoping boom 104 in orderto re-tension the one or more elastic cords (128,130) and/or the aftstay 118, lower net line 122, and/or net line 132. The position of theboom 104 may be self-centering in the first position before or afterimpact of the SUAV 109.

FIG. 1D depicts a top view of the exemplary shipboard recovery system100 as the triangular net 124 billows outwards due to the wind direction136, and the closing speed of the SUAV 109 is reduced. The shipboardrecovery system 100 may progressively transfer the energy of the SUAV109 impact. The lower net line 122 is depicted with dashed lines. Thetriangular net 124 is supported on each side by a corresponding line(118, 122, 132). The entire shipboard recovery system 100 may bedisposed over the side of the ship 106 so as to not use any, or minimal,deck space. The position of the shipboard recovery system 100 may alsoreduce turbulence caused by one or more structures on the ship blowingover the triangular net 124. The ship may be moving in a forwarddirection 138, which may oppose any one of a number of wind directions136. This movement of the ship and/or wind direction 136 may cause thetriangular net 124 to billow outwards. A visual target 140, e.g., asolid material having a thickness greater than that of the net material,may be located in a center of the triangular net 124. The visual target140 may have increased wind resistance and assist in creating thebillowing shape of the triangular net 124. It may be desirable to reducethe closing speed of the SUAV 109 prior to impact with the shipboardrecovery system 100. An optimum closing speed may be, for example, 12meters/second. The engine of the SUAV 109 may be switched off prior toimpact to further reduce the closing speed, e.g., by cutting power to apropeller of the SUAV 109.

FIG. 1E depicts a top view of the exemplary shipboard recovery system100 of FIG. 1D as the triangular net 124 is deformed due to SUAV 109impact. The recovery system 100 may progressively transfer the energy ofthe SUAV 109 impact. Energy may be transferred by a deformation of thetriangular net 124 as it is deformed from its initial, billowing, state.The triangular net 124 may continue to deform until resistance is met.

FIG. 1F depicts a top view of the exemplary shipboard recovery system100 of FIGS. 1D-1E as the impact of the SUAV 109 causes deformation ofthe elastic cords (128, 130) and lines (118, 122, 132) connected to thenet. Upon deformation of the triangular net 124, the one or more elasticcords (128, 130) may be deformed to continue to progressively transferthe energy of the SUAV 109 impact. By transferring the energy via theelastic cords (128, 130), the boom 104 and/or mast may be protected fromforces that may cause them to shatter or otherwise fail. The lines (118,122, 132) surrounding the triangular net 124 may also deform as theenergy of the SUAV 109 impact is progressively transferred to the system100.

FIG. 1G depicts a top view of the exemplary shipboard recovery system100 of FIGS. 1D-1F as the impact of the SUAV 109 causes the boom to lift142 vertically relative to the ship's deck, and progressively bend. Theboom 104 may lift vertically via a horizontal hinge in the gooseneckconnector 108. The height to which the weight of the boom is lifted maydynamically vary based on the energy of the SUAV 109 impact to betransferred. The boom 104 may also progressively bend in response to theSUAV 109 impact, where the end of the boom may bend first, followed by abending and/or lifting of the boom 104 proximate to the gooseneckconnector 108.

FIG. 1H depicts a top view of the exemplary shipboard recovery system100 of FIGS. 1D-1G as the impact of the SUAV 109 causes the boom 104 torotate 144 horizontally relative to the ship's deck towards the bow ofthe ship 106. The rotation 144 of the boom may be to convert additionalkinetic energy from the SUAV 109 impact and prevent damage to the boom104 and/or mast 102. Accordingly, each element of the system 100described in FIGS. 1D-1H acts to progressively absorb the impact of theSUAV 109.

FIG. 2A depicts the exemplary triangular net 124 having lines (118, 122,132) secured to each side of the net and elastic cords (128, 130)secured to one or more corners of the triangular net 124. Three or morerings 200 may be attached to the perimeter of the triangular net 124 andthe lines (118, 122, 132) may be slidably connected to the triangularnet 124 by being threaded through these rings. The triangular net 124may have a square mesh shape with a perpendicular orientation of themesh, although other shapes and orientations may be used. The squaremesh size may be smaller than the cross-sectional size of the fuselageof the SUAV, so that the SUAV fuselage does not squeeze through thetriangular net 124 upon impact. The square mesh size should be largeenough so as to minimize the weight of the triangular net 124 and reducethe effects of windage on the triangular net 124. The triangular net 124may be made from an ultra-high-molecular-weight polyethylene (UHMWPE,UHMW) such as Dyneema®. UHMWPE has extremely low moisture absorption anda very low coefficient of friction, is self-lubricating, and is highlyresistant to abrasion. The UHMWPE may have a small diameter to limit theeffect of weight and/or windage, e.g., 1.2 mm in diameter.

The triangular net 124 may include a visual target 140, e.g., a crossnear the center of the triangular net 124. The visual target 140 may beused as a visual reference as the triangular net 124 may appearpractically transparent due to its thin material and/or surroundingenvironment. The triangular net 124 may be located off the side of theship so that it does not take up deck space and may not be in directline of the ship crew and/or equipment in case of a failed landing. Thelocation of the triangular 124 off the side of the ship may also reducethe wind turbulence created by the structure of the ship. The mesh ofthe triangular net 124 may capture the SUAV by detachable entanglementof one or more components of the SUAV, e.g., propeller, wingtips,fuselage, sensors, etc. The mesh of the triangular net 124 may alsocapture the SUAV 109 by detachable entanglement of one or more barbsdisposed on a fuselage of the SUAV 109 (See FIGS. 3A-3B). The slope ofthe triangular net 124 may be approximately forty-five degrees to ensurethat the SUAV does not exit the triangular net 124 after impact and toreduce the impact of the SUAV. The weight of the SUAV may be cradled inthe triangular net 124 after impact. In some embodiments with barbsconnected to the fuselage of the SUAV, the slope of the triangular net124 may be at, or near, vertical.

The triangular net 124 may have one or more elastic cords (128, 130)secured to one or more corners of the triangular net 124. Each elasticcord (128, 130) may be bundled together, e.g., two or more substantiallyparallel elastic cords held together with silicon tape, and connected toa corresponding line (132, 122). The corresponding lines (132, 122) mayeach have a corresponding check line (204, 206) for when the elasticcords (128, 130) stretch to their maximum length and/or fail. The endsof each line (118, 122, 132) may have a detachable attachment 208, e.g.,a carabiner, for attaching to a portion of the ship, boom, and/or mast.

FIG. 2B depicts an exemplary ring 200 secured to a side of thetriangular net 124 for attachment to a line along the side of the net.The ring 200 may be attached 207, e.g., via knotted net material, to theperimeter of the triangular net 124 at a set spacing, e.g., one ring 200per foot. A line, such as the lower net line 122, may be threadedthrough these rings 200 so that the triangular net 124 may move freelyrelative to the lower net line 122, e.g., when setting up the system orupon impact of the SUAV. The ring may be made from a material having lowfriction, e.g., Teflon® by DuPont™, so that the triangular net 124 maydeform upon without compromising the line structure. By allowing the netto move freely relative to the lines, via the rings 200, the system mayabsorb more energy from the SUAV impact and a system failure, e.g.,breaking of the mast and/or boom, may be prevented.

FIG. 3A depicts a side view of an exemplary barb 300 secured to afuselage 302 of the SUAV 109. One or more barbs 300 may be attached tothe fuselage 302 of the SUAV 109. The barb 300 may be detachablyattached, e.g., by a screw 304, to the fuselage 302. In someembodiments, the barb 300 may be fixedly attached to the SUAV 109. Thebarb may have a first bend 306 and a second bend 308 to allow the barb300 to catch on the net upon impact and prevent the SUAV 109 fromfalling out of the net. In some embodiments, the barb may have a marker310, e.g., colored tape, so that a deck handler can easily identify thebarb 300 and detach it from the net after impact.

FIG. 3B depicts a top view of four exemplary barbs (300, 312, 314, 316)secured to the fuselage 302 of the SUAV 109 near, and/or about, a centerof mass 318 of the SUAV 109. An SUAV may be equipped with one or morebarbs (300, 312, 314, 316). These barbs (300, 312, 314, 316) may beplaced near, and/or about, the center of mass 318, e.g., location of anSUAV battery, of the SUAV 109 so as to increase the likelihood of thebarbs (300, 312, 314, 316) attaching to the net after impact, and notchanging the center of gravity location and/or balance of the SUAV 109when added thereto. In some embodiments, the barbs (300, 312, 314, 316)may be placed on other components on the SUAV, e.g., wing tips, tails,etc. The location of the barbs (300, 312, 314, 316) should avoidinterference with other SUAV 109 components, e.g., cameras, sensors,etc.

FIG. 4A depicts the exemplary gooseneck connector 108 attached to a ship106 stanchion 110 by a lower clamp 112 and an upper clamp 400 with theboom 104 extended away from the ship 106. The gooseneck connector 108may be detachably attached to the ship 106 stanchion 110 by the lowerclamp 112. In some embodiments, the lower clamp 112 may be a bracket.The lower clamp 112 may include a clamp quick release block 402, whichmay receive a gooseneck connector quick release block 404 (See FIGS.5A-5B). The lower clamp 112 may be attached to a stanchion 110. Then,the gooseneck connector quick release block 404 may be detachablyattached to the clamp quick release block 402. The weight of thegooseneck connector 108, mast 102, boom 104, and other components of thesystem do not need to be on the lower clamp 112 as the lower clamp 112is being attached. An individual may attach the lower clamp 112 to thestanchion 110 without requiring assistance in supporting the rest of theweight of the system. Once the lower clamp 112 is attached, the rest ofthe system may be attached via the quick release connection, securedwith a quick release pin 405, between the clamp quick release block 402and the gooseneck connector quick release block 404. In someembodiments, the gooseneck connector 108 may be directly connected tothe lower clamp 112. In other embodiments, an alternative connectionbetween the lower clamp 112 and gooseneck connector 108 may be used.

A mast connector 406 may be connected to the gooseneck connector quickrelease block 404. The mast connector 406 may receive the mast 102. Themast connector 406 may secure the mast 102 via a mast connector pin 408.Once the gooseneck connector 108 is attached to the stanchion 110, adeck hand may attach an upper clamp 400 around the stanchion 110 andmast 102. The upper clamp 400 may provide additional stability to thesystem, especially during upright storage (See FIG. 6). The upper clamp400 may be made from a thermoplastic such as polyoxymethylene (POM)having high stiffness, low friction, and dimensional stability, e.g.,Delrin® by DuPont™. In some embodiments, the upper clamp 400 may befurther secured with an elastic cord. The upper clamp 400 may haveinfinite height adjustment along the stanchion 110 relative to the lowerclamp 112. The upper clamp 400 may be positioned to avoid objects on thestanchion 110, e.g., a lifeline connected to the stanchion 110. Amaximum possible distance between the upper clamp 400 and the lowerclamp 112 is optimal for support of the system.

The gooseneck connector 108 may include a vertical hinge 410 and ahorizontal hinge 412. A boom connector 414 may be connected to thehorizontal hinge 412. The boom connector 414 may receive the boom 104.The boom connector 414 may secure the boom 104 via a boom connector pin416. The vertical hinge 410, having a vertical axis of rotation relativeto the pin position, may allow the boom 104 to rotate horizontally, fromaft to stern, relative to the ship's deck. The horizontal hinge 412,having a horizontal axis of rotation relative to the pin position, mayallow the boom 104 to rotate vertically relative to the ship's deck.

FIG. 4B depicts the exemplary gooseneck connector 108 of FIG. 4A showingvertical and horizontal rotation of the boom 104. The weight of the boom104 may dynamically absorb the energy of the SUAV as it impacts thetriangular net based on how high the boom 104 is rotated vertically, viathe horizontal hinge 412; how far the boom 104 is rotated horizontally,via the vertical hinge 410; and/or how much the boom 104 isprogressively flexed from its first position before SUAV impact.

FIG. 5A depicts a quick release system between the exemplary lower clamp112 and the gooseneck connector quick release block 404 with anindentation 500 in the clamp quick release block 402 shown with dottedlines. The lower clamp 112 may be detachably attached to a stanchion,e.g., via one or more screws 502. The lower clamp may be fixedlyattached to the clamp quick release block 402. In some embodiments, theclamp and quick release block may be a single part. The gooseneckconnector quick release block 404 may have a protrusion 504 sized to fitin the indentation 500 of the clamp quick release block 402. Once theprotrusion 504 is in the indentation 500, the quick release pin 405 maybe inserted to secure the gooseneck connector quick release block 404 tothe clamp quick release block 402. The gooseneck connector quick releaseblock 404 may be removed from the clamp quick release block 402 byremoving the quick release pin 405 and lifting the gooseneck connectorquick release block 404 up and away from the clamp quick release block402. The gooseneck connector quick release block 404 and/or clamp quickrelease block 402 may have one or more angled, or curved, edges toassist in connection and/or removal. The protrusion 504 and/orindentation 500 may have one or more corresponding curved, or angled,edges to assist in insertion and/or removal of the protrusion 504 fromthe indentation 500.

FIG. 5B depicts a quick release system between a second lower clamp 508sized for a different stanchion and the gooseneck connector quickrelease block 404 shown in FIG. 5A with a second indentation 510 in thesecond clamp quick release block 512 shown with dotted lines. Some shipsmay have different sized stanchions that require different clamps toaccommodate them. The second lower clamp 508 may be used to attach thesystem to a different sized stanchion than the lower clamp (112, SeeFIG. 5A). In some embodiments, a second upper clamp (not shown) may beused with the corresponding second lower clamp 508 to fit differentsized stanchions. The gooseneck connector quick release block 404 may beconnected to the second quick release block 512 by inserting theprotrusion 504 into the second indentation 510 and securing theconnection via the quick release pin 405. By using a standard size forthe protrusion 504 and accompanying indentations, the system may beattached to various stanchions by utilizing various lower clamps sizedto accommodate various stanchions.

FIG. 6 depicts the system in a stored state with the mast 102 and boom104 extending vertically and a tether 600 attached from the gooseneckconnector 108 to another portion of the ship 106. The system may beplaced in the stored state as long as the weather conditions do notexceed a threshold, e.g., World Meteorological Organization (WMO) seastate four conditions in which wave height is between 1.25 meters and2.5 meters. In bad weather conditions, e.g., above WMO sea state four,the system may be detached, via the quick release (See FIGS. 5A-5B), andstored on the ship 106. The system may be secured with a tether 600connected between a portion of the gooseneck connector, i.e., thegooseneck connector quick release block, horizontal hinge, and/orvertical hinge, to another portion of the ship 106, e.g., a verticalrailing stanchion on the ship 106. In some embodiments, the system maybe stored in a carry bag and the tether 600 may act as a carryinghandle, with tether connected between the gooseneck connector 108 and aconnector on an outside of the carry bag.

FIG. 7 is a flowchart of a setup of an exemplary embodiment of the SUAVshipboard recovery system 700. The lower clamp may be attached to astanchion, e.g., a vertical railing on the perimeter of the ship's deck(step 702). Next, the gooseneck connector may be attached to the lowerclamp via a quick release (step 704). In some embodiments, gooseneckconnector may be directly connected to the lower clamp, but this mayrequire an individual to support the weight of the system while thelower clamp is attached. The upper clamp may be attached around an upperportion of the stanchion and mast (step 706). The upper clamp may beused to provide additional stability to the system, especially duringstorage (See FIG. 6). In some embodiments, the upper clamp may not beneeded and the lower clamp may be the only point of contact between thesystem and the stanchion of the ship. Tensioned rigging may be attachedfrom a top of the mast to the ship to provide support to the mast (step708). Running rigging may be attached from the tip of the boom to theship (step 710). In some embodiments, portions of the tensioned riggingand/or running rigging may be integrated into the edge of the net andmay already be attached to corresponding components in the system. Theboom may be retracted perpendicular to the mast (step 712). Inembodiments where the system is attached to a stanchion on a ship, theboom may extend over an edge of the ship and perpendicular to the ship'sside. Corners of the net may be attached as needed (step 714). Certaincorners of the net may already be attached via the running riggingand/or tensioned rigging. In some embodiments, the corners of the netmay be attached with elastic cords, e.g., bungee cords. The elasticcords may be tensioned by tightening the running rigging (step 716).

FIG. 8 is a flowchart of an exemplary embodiment of the SUAV shipboardrecovery system 800. The SUAV may be launched (step 802). The SUAV maybe launched from the ship having the recovery system or from anothership or object. The SUAV may be guided into the net (step 804). Theenergy of the SUAV impact may be progressively absorbed by: deformationof the net; deformation of one or more tensioned elastic cords; bendingof the boom; vertical rotation of the boom in the direction of SUAVimpact; and horizontal rotation of the boom away from the direction ofSUAV impact (step 806). The SUAV may be secured in the net by detachableentanglement of one or more SUAV components and/or barbs (step 808). Toretrieve the SUAV, the telescoping mast may be lowered and/or therunning rigging may be let out to rotate boom proximate to ship's deck'sedge (step 810). The SUAV may be retrieved by the deck handler (step812). As the SUAV may only be slightly entangled and/or attached via oneor more barbs, the time required to remove the SUAV from the net is farless than if the SUAV were completely tangled in the net. If desired,the SUAV may be quickly relaunched, e.g., within approximately thirtyseconds of impact with the net (step 814).

The exemplary SUAV shipboard recovery system may be disposed over theside of a moving ship such that turbulence from the ship structure isminimized. The ship may be moving in a windward direction such that thenet billows out towards an aft of the ship. This positioning ensuresthat the speed differential at the time of impact, i.e., closing speed,is reduced. This positioning may also ensure that the net has a greatereffective mass, and further reduce the impact into the net.

It is contemplated that various combinations and/or sub-combinations ofthe specific features and aspects of the above embodiments may be madeand still fall within the scope of the invention. Accordingly, it shouldbe understood that various features and aspects of the disclosedembodiments may be combined with or substituted for one another in orderto form varying modes of the disclosed invention. Further it is intendedthat the scope of the present invention is herein disclosed by way ofexamples and should not be limited by the particular disclosedembodiments described above.

What is claimed is:
 1. A method comprising: impacting, by a smallunmanned aerial vehicle (SUAV), a net having at least three sides; andconverting the kinetic energy of the SUAV into at least one of: elasticpotential energy of one or more tensioned elastic cords connected to thenet, gravitational potential energy of a frame member connected to thenet, rotational kinetic energy of the frame member connected to the net,and elastic potential energy of the frame member connected to the net;wherein the frame member is connected to a connector having a verticalhinge and a horizontal hinge; and wherein a second elongate frame memberis stationary and connected at the connector.
 2. The method of claim 1further comprising: securing the SUAV in the net after converting thekinetic energy of the SUAV by detachable entanglement of the SUAV in thenet.
 3. The method of claim 2 wherein securing the SUAV in the netfurther comprises: detachably entangling at least one barb in the net,wherein the at least one barb is disposed on a fuselage of the SUAV. 4.The method of claim 1 wherein at least one corner of the net isconnected to a portion of a ship.
 5. The method of claim 4 furthercomprising: removing, by a deck handler on the ship, the SUAV from thenet.
 6. The method of claim 1, wherein the frame member is a boom. 7.The method of claim 6 further comprising: rotating the boom to alocation proximate to an edge of a ship.
 8. The method of claim 1,wherein the second frame member is a mast and the net is connected tothe mast.
 9. The method of claim 8 further comprising: lowering the masttelescopically.
 10. The method of claim 1 further comprising: reducing,prior to impact, a closing speed of the SUAV.
 11. The method of claim 10wherein reducing the speed of the SUAV further comprises cutting powerto a propeller of the SUAV.
 12. A small unmanned aerial vehicle (SUAV)recovery system comprising: a net having at least three corners; and aboom connected to at least one corner of the net; and a mast, whereinthe mast is stationary; a connector, wherein the mast and the boom areconnected at the connector; wherein energy of an impact of the SUAV intothe net is progressively transferred by at least one of: a verticalrotation of the boom in a direction towards the impact of the SUAV, anda horizontal rotation of the boom in a direction away from the impact ofthe SUAV.
 13. The SUAV recovery system of claim 12 wherein energy of theimpact of the SUAV is also transferred by deformation of the net. 14.The SUAV recovery system of claim 12 wherein energy of the impact of theSUAV is also transferred by a progressive bending of the boom.
 15. TheSUAV recovery system of claim 12 further comprising: one or moretensioned elastic cords attached to at least one corner of the net;wherein energy of the impact of the SUAV is also transferred bydeformation of the one or more tensioned elastic cords.
 16. The SUAVrecovery system of claim 12 further comprising: three or more ringsattached to the perimeter of the net; and three or more lines, whereineach side of the net is slidably connected to one of the three or morelines by one or more of the three or more rings.
 17. The SUAV recoverysystem of claim 12, wherein the mast is oriented perpendicular to theboom, and wherein the mast and the boom are telescopically adjustable inlength.
 18. The SUAV recovery system of claim 12 wherein a square meshsize of the net is smaller than a cross-sectional size of a fuselage ofthe SUAV.
 19. The SUAV recovery system of claim 12 further comprising:one or more barbs disposed on a fuselage of the SUAV, wherein the one ormore barbs are sized to detachably entangle in the net after impact.